A new study has found that autism diagnoses in the UK are increasingly linked to prior conditions such as anxiety, depression, sleep disorders, ADHD, stress-related disorders, eating disorders, headaches and chronic fatigue.
Researchers analysed data from the UK and Sweden and wrote in the journal BMJ Mental Health that “autism diagnoses have risen consistently over time”. In the UK, rates of new diagnoses increased from six per 100,000 people in 2010 to 64 per 100,000 in 2023.
Changing Profile of Newly Diagnosed Adults
Experts found a decline in people being diagnosed with autism who also had conditions such as epilepsy and intellectual disability, and a rise in those who also suffered from stress, eating disorders, headaches and chronic fatigue. They also found a rapid rise in autism diagnoses among 16 to 20-year-olds since 2010 in the UK, alongside a rise in women and white people compared to other ethnicities.
“Over time, there has been a consistent decline in the proportion of autistic adults with a prior diagnosis of epilepsy, psychosis and intellectual disability, and an increase in the proportion with a prior diagnosis of attention-deficit hyperactivity disorder (ADHD), anxiety, depression and several other mental illnesses,” researchers said.
Changes in Co-Occurring Conditions
Overall, autism rose in people who had been previously diagnosed with anxiety, depression, sleep disorders, ADHD, stress-related disorders, eating disorders, headaches and chronic fatigue, as well as use of antidepressants, melatonin, opioids and gabapentin. In one example, the proportion of autistic adults with prior records of epilepsy in the UK decreased from 10% in 2010 to 4% in 2023. Meanwhile, those with a history of anxiety increased from 28.7% to 58.3%.
The team included experts from the Medical Research Council’s integrative epidemiology unit at the University of Bristol and Avon and Wiltshire Mental Health Partnership NHS Trust. They said there could be several potential explanations for the findings, including changes to diagnostic manuals and greater appreciation of nuanced forms of autism that may have previously been labelled as other conditions, particularly in females.
Implications and Expert Views
In the UK, 24.5 million adults contributed to the study, including 141,119 with an autism diagnosis. In Sweden, more than nine million were involved, of whom around 100,000 had an autism diagnosis. A first recorded adult autism diagnosis was consistently higher in Sweden than the UK, but incidence increased rapidly in the UK after 2020. New diagnoses also rose fastest in females in both nations, as well as in people of white ethnicity in the UK.
Dr Monique Botha, associate professor in social and developmental psychology at Durham University, said studies have shown repeatedly that “autistic adults are more likely to have depression, anxiety, self-harm, and suicidal ideation regardless of whether those diagnoses or the developmental ones came first”. She added that the findings may “reflect the cumulative consequences of historical diagnostic inequalities rather than changing diagnostic boundaries”.
Last month, a Government-ordered review concluded the UK is at a “tipping point” where people are at risk of being misdiagnosed with ADHD and autism. The team said overdiagnosis can lead to “over-medicalisation” where ordinary, healthy, life experiences are turned into medical problems.
